The Effect of Water and Sucrose Solution on Plant Tissue

The Effect of Water and Sucrose Solution on Plant Tissue
I am going to investigate the change in size and weight of a potato when bathed in the water, dilute sugar solution and concentrated sucrose. This investigation will take place under the Osmosis theory. Osmosis will cause the water molecules to travel in and out of the plant cell. Aim: To investigate the effect of varying concentration of a certain sugar solutions on the amount of osmotic activity between the solution and a potato chip of a given size. Method ? First we are going to collect 6 boiling tubes each containing a concentration of sugar solution between 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 Mol DM -3. ? We will then get a Cork borer of size 3; we will then insert it through the potato so we could achieve our cylindrical shape. ? We will then measure out the potato samples to 3cm using the Vernier callipers. We will cut the potato samples for fine adjustment. ? We will then weigh the potato samples using the electronic weighing scales. ? We will then place the 18 potato samples in the test tubes each containing the different type of solutions. We will have two test tubes for each amount of mol. Each test tube will contain 3 potato samples. ? We will then leave the potato samples in the solutions for about half an hour. We will use one test tube for each Mol DM -3 which increases by 0.2 each time and then get an average. ? We will then measure and weigh each of the potato samples.
We will then record the differences onto a table of results. Equipments list ? Scalpel ? Cork borer ? 6 Test tubes ? Test tube rack ? Potato ? Vernier callipers ? Sugar solution ? Chopping board ? Water solution ? Weighing scales Why? ? We will use a scalpel to cut the potato to the required length ? We will use a cork borer to collect our potato samples in a cylindrical shape. ? We will get 6 test tubes because each test tube will contain 3 potato samples and a recorded concentration of solution. ? We will collect a test tube rack so we can place the test tubes inside it. ? I will use a potato to collect my samples because it?s a plant and it?s what we were asked to investigate. ? We will use vernier callipers to measure the potato samples so we could measure them to two decimal places. ? We will use different concentrations of sugar solution so we can investigate the changes between different concentrations. ? I will use a weighing scale to measure the weight of the potato samples accurately before and after the investigation. To make this experiment as productive as possible I will be varying the concentration of the sucrose. The concentration of sucrose will vary from 0.0. to 1.0 Mol DM -3. To make this experiment as accurate as possible, I am going to collect two types of results and then achieving the average. I am also going to use vernier capillaries which will give me results to 2 decimal places which will keep the measurements as accurate as possible. In order of keeping the weights as accurate as possible I will be using electrical weighing scales. I am going to do the following things in order to make this experiment a fair test: ? For the purpose of my experiment I am going to do all the experiments at room temperature. ? the water potential of the potato initially will be kept the same by using the same type of potato, which have been treated in the same way, e.g. have all been cut without being washed and peeled. ? The mass of the potato is a dependent variable, and this means that it will be measured throughout the experiment. I will measure the mass in grams. The potato chip will be measured before it is put in the solution, and after. This will allow us to see whether osmosis has taken place, and to what extent. ? The volume of the solution that the potato chips are kept in must be fair. The must be totally covered in the solution, and the amount of solution will be kept the same because all the potato chips are roughly same size. ? I am also going to use the same balance to weigh my potato chips. This is because the measurements may slightly vary between scales. We used an electronic scale for highest accuracy. ? I am going to use the same type of potato for every single sample. ? The same person in my group will be doing the measuring and a different person will be doing all the weighing before and after the experiment. ? The same member of my group will measure out the solutions in the test tube. Once I have completed the experiment I will be measuring and weighing the potato samples, I will see if the potato samples have increased or decreased in weight or size depending on the concentrations of sucrose and water. I will also be investigating my results to see if they support the theory of osmosis. Osmosis theory Osmosis is a special type of diffusion. It is the movement of water through a partially permeable membrane. Suppose water is separated from a sugar solution by a membrane which is permeable to water molecules, but impermeable to sugar molecules. The pure water will have a high concentration of water molecules, whereas the sugar solution will contain low concentration of water molecules. Therefore the water molecules will then diffuse through the partially permeable membrane from the region of high water concentration to a region of low water concentration. This will result in even distribution. High concentration of water Low concentration of water Molecules Molecules [image] The diagram shows us the diffusion theory for osmosis. As you can see the water molecules are leaving the region of high concentration of water molecules (dilute solution) and are entering the region of low concentration of water molecules (strong solution) through the partially permeable membrane. Osmosis will only occur provided a weak solution is separated from a strong solution by a partially permeable membrane. Some sugar molecules do pass through pores but at a much slower rate. The diagram below shows the result of the plant cell after the osmosis has taken place when it has been placed in different solutions. [image] The picture above shows us the result of a cell when water enters through the partially permeable membrane. The diagram on the right which is labelled Turged shows us the cell when a more dilute mixture (water) enters the cell. The water diffuses through the freely permeable cell wall and selectively permeable membrane and enters the vacuole. The vacuole swells and pushes the cytoplasm against the cell wall. On the other side of the diagram we are shown what happens when the cell is bathed in a strong solution. The water leaves the cell by osmosis, the vacuole shrinks and the cytoplasm is pulled away from the cell wall. The cell in this condition is said to be Plasmotised. The sugar solution enters the space between the cell wall and cytoplasm. A dilute solution will have a higher water potential than a concentrated solution. In the textbook gcse Biology by D.G.Mackean it says ?The water potential of a solution is a measure of whether it is likely to lose or gain water molecules from another solution. Pure water has the highest possible water potential because water molecules will flow it to any other aqueous solution, no matter how dilute.? The scientific knowledge supports my prediction that the more dilute solutions will enter the cell and cause it to swell and become turged. Whereas the more concentrated solutions will cause the cytoplasm to shrink away from the cell wall and become plasmotised. We carried out a preliminary experiment before in class to help us with our actual experiment. The preliminary experiment helped us decide what size cork borer to use. It showed us what size was the best for gaining good results at minimum time. It also helped decide how long the potato cylinder would be. We used a potato in our preliminary experiment so we could test whether a potato would give us accurate results. This experiment also gave us practise on how to use the vernier callipers. This made sure that the length of our potatoes was accurate. The preliminary experiment helped us decide what a suitable time was to keep the potato samples in the solution, in order there is a significant change in the size and length of the potatoes so we gain outstanding results. results table for the change IN mass Concentration of sucrose 1.0 mdm -3 each test tube had 3 samples total Mass before** Total Mass after** 0 6.40g 6.46g Average of titles** 2.133g 2.1533g Ave % inc/dec Before investigation 0% 0.92% inc 0.2 6.26g 6.36g Average of titles** 2.0866g 2.12g Ave % inc/dec Before investigation 0% 1.5977% inc 0.4 6.28g 6.49g Average of titles ** 2.0933g 2.1633g Ave % inc/dec Before investigation 0% 3.32804% inc 0.6 6.20g 5.68g Average of titles** 2.0666g 1.893g Ave % inc/dec Before investigation 0% 8.796% dec 0.8 6.22g 5.62g Average of titles** 2.0733g 1.873g Ave % inc/dec Before investigation 0% 9.662% dec 1.0 6.35g 5.66g Average of titles** 2.11666g 1.886667g Ave % inc/dec Before investigation 0% 10.8966% dec results table for the change IN length Concentration of sucrose 1.0 mdm -3 each test tube had 3 samples Length before** Length after** 0 133.5mm 135.3mm Average of titles** 44.5mm 45.1mm Ave % inc/dec Before investigation 0% 1.348% inc 0.2 135.6mm 136mm Average of titles** 45.2mm 45.3333mm Ave % inc/dec Before investigation 0% 0.29498% inc 0.4 134.4mm 134.6mm Average of titles** 44.8mm 44.8666mm Ave % inc/dec Before investigation 0% 0.148809508%inc 0.6 131.6mm 128.8mm Average of titles** 43.8666mm 42.93333mm Ave % inc/dec Before investigation 0% 2.127659649% dec 0.8 132.8mm 130.4mm Average of titles** 44.2666mm 43.466667mm Ave % inc/dec Before investigation 0% 1.8072% dec 1.0 138.6mm 135.3mm Average of titles** 46.2mm 45.1mm Ave % inc/dec Before investigation 0% 2.30895% dec All of my results that were gained were all correct to 2 decimal places. The mass of my results were found out using an electrical weighing scale, the mass was measured using grams. To work out the length of the potato samples we used vernier callipers, the length was measured using millimetres. In order my results were accurate I gained three sets of results and then got an average. To work out any changes in any of the potato samples we worked them out using percentages. I have found from my results that the when there was an increase in the concentration of the sucrose solution there would be a decrease in the mass and length of the potato sample. The higher the concentration of the sucrose solution the more decrease there is in the mass and length of the potato samples. When the concentration of sucrose solution reaches about 0.6 Mol DM -3 the mass and length of the potato samples decrease. These results support my hypothesis. conclusion From this investigation I have found that the higher concentration of sucrose solution in the test tubes, the lower the mass and length of the plant cell. This is because when the cell is bathed in a concentrated solution the water leaves the cell by osmosis, the vacuole shrinks and the cytoplasm is pulled away from the cell wall. The cell in this condition is said to be Plasmotised. The sugar solution enters the space between the cell wall and cytoplasm. The cell decreases in volume and length. This happened when the cell was bathed in sucrose solution which had a concentration of 0.6 Mol DM -3 or higher. When the cell was bathed in a sucrose solution of concentration 0.4 Mol DM -3 there was an increase in the mass and length of the plant cell. When a cell is bathed in a more dilute solution it increases in size and it?s said to have become Turged. This is because when water diffuses through the freely permeable cell wall and selectively permeable membrane it enters the vacuole. The vacuole swells and pushes the cytoplasm against the cell wall. This results in the increase of size. From my graph (next page) I have found a reasonable pattern which supports my prediction and osmosis theory. It appears that the line of best fit is decreasing as the concentration of sucrose solution increases (x axis). Which points out that length and mass of the potato samples (y axis) must be decreasing. Due to the osmosis effect of plasmosis. My conclusion does support my previous prediction that the more dilute solutions will enter the cell and cause it to swell and become Turged. Whereas the more concentrated solutions will cause the cytoplasm to shrink away from the cell wall and become Plasmotised. The potato samples that were in the test tubes that contained the sucrose solution of concentration 0.4 Mol DM -3 or less had increased in mass and length. On the other hand the potato samples that were in the test tubes which contained the sucrose solution of concentration 0.6 Mol DM -3 or more had decreased in mass and length. evaluation I think my investigation went pretty well. I am very pleased with the results I gained because they had shown me a good trend/pattern which I could refer to. My graphs showed me a good set of results which I really expected. Both graphs had a curve of best fit decreasing which represented the results gained. The graphs had curves travelling downwards which I pretty much expected, because as the concentration increased the change decreased which meant that the curve would travel downwards and across. There was one or two anomalous gained from my graph, this might have been because of the human errors in measuring and weighing. I think the procedure I used was quite suitable for this experiment because there was quiet a lot of variation in the concentration of the sucrose solution. I varied my sucrose concentration from 0.2 to 1.0 Mol DM -3 which gave us results which covered most solutions. For each concentration I investigated I used one boiling tube with three potato samples inside so I could get an average which would give me accurate results. To measure my potato samples I used the vernier callipers which would measure the samples to 2 decimal places which gave me accurate measurements. I also used the electrical weighing scales to weigh my potato samples which improved the accuracy. I could have improved the procedure of the experiment by having more test tubes for each concentration and an increased number of concentrations then I would be able to get more accurate and an enhanced range of results. I could have left my experiment under observation for a longer time (over an hour) to see further differences in length and weight. There were not any out of the ordinary results, but some were not as close to the line as others. This may have been caused by human error. When the potato chips were removed from the test tubes and dried I may well have dried some potatoes more thoroughly than others and so some would have more excess water, which would add to the mass. If the experiment was repeated I could find another way to dry the potatoes that would ensure that all were dried in the same way for the same time. However with all this said I think that the experiment was truly successful and I was very pleased with the complete comparison of my results with my initial prediction. I think my results were quite reliable. They weren?t a reliable as I would have liked. There were quite a few problems which affected my results. The heat intensity of the sunlight and humidity of the classroom could have affected the results. The room temperature was a major factor in the experiment as it could have affected the rate of osmosis. Another thing which could have affected my results was when we were cutting, measuring and weighing the potato samples, the first potato samples that were investigated could have changed in size by the time all of the potato samples were investigated. I think that my results are sufficient enough to form a conclusion because from my investigation I have come to the conclusion that as the concentration of the sucrose solution increases the weight and length of the potato samples decrease. This conclusion that I have found agrees with the osmosis theory that if a cell is bathed in a concentrated solution, the cell would shrink in size and become plasmotised. There were a number of anomalous results in my investigation. This might have occurred because:- ? The potato samples were left out to long during the investigation of each potato sample. ? The sunlight and humidity of the classroom could have affected the sample. ? There might have been a human error with the measuring and weighing from a group member. ? The potato sample might have been damaged during the course of the experiment. I could have carried out some further work on this investigation to extend and broaden my results. I could have investigated other vegetables such as carrots. I could have also increased the sugar concentration to find out when a plant cell could finally stop decreasing in size. I could have done another investigation using the same vegetable but this time using a salt concentrated solution. I could compare the results. I could have investigated different plants such as marsh plants to see if different plant cells living in different conditions could affect the results and not agree with the osmosis theory.

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